Low energy X and Gamma ray sources such as Cs-131 (9.7 Days T1/2, 30 keV) are extremely useful in cancer therapy with obvious advantages such as ease of shielding, useful range in tissue. Since Cs-131 is capable of forming insoluble metal complexes with metal salts such as Ammonium Molybdophosphate, it is intended to exploit this property of Cesium in the proposed study. The purpose of the present study is to explore the feasibility of commercially manufacturing radioactive sources of Cs-131 technologically superior and better capable than existing ones, of providing uniform distribution of radioactivity and desirable safety characteristics. We plan to accomplish the proposed project as follows: a. Complex formation with a suitable metal as a substrate, from which Cesium does not dissociate. b. Seed manufacture, consisting of central tungsten core coated with a suitable metal complex; film manufacture, consisting of suitable membrane coated with a suitable metal complex. c. Evaluation of radioactive source integrity against leakage using conventional procedures. d. Evaluation of uniformity of dose distribution in the radioactive source and clinical potential by dose and dose rate measurements.